The present invention relates to the drive circuit for a thin-film EL display panel and more particularly, to a drive circuit which is substantially of the AC-driven capacitor-type for a flat matrix display panel driven by voltages.
Both the double-insulation or triple-insulation type of thin-film EL display panel are typically constructed as follows. As shown in FIG. 2, a plurality of belt-shaped transparent electrodes 2 composed of In.sub.2 O.sub.3 are formed onto a glass substrate 1 parallel to each other. Then, conductive layers 3 composed of, for example, Y.sub.2 O.sub.3, Si.sub.3 N.sub.4, TiO.sub.2 or Al.sub.2 O.sub.3, an EL layer 4 composed of ZnS containing a doped activating agent such as Mn, and an identical conductive layer 3' composed of either Y.sub.2 O.sub.3, Si.sub.3 N.sub.4, TiO.sub.2 or Al.sub.2 O.sub.3 are laid sequentially employing any thin-film adhesion technology such as vapor-phase adhesion or the sputtering process to form a triple-layered structure having a thickness of from 500 to a maximum of 10,000 angstroms. Then, belt-shaped rear surface electrodes 5 composed of Al.sub.2 O.sub.3 are installed parallel to each other so that they cross the transparent electrodes 2 at right angles. Since the thin-film EL display panel is provided with an EL layer 4 sandwiched between electrodes by the conductive layers 3 and 3', such a thin-film EL display panel can be considered as a capacitive element from the viewpoint of an equivalent circuit. As is clear from the graphic chart denoting the relationship between voltages and the luminance characteristics shown by the solid line in FIG. 3, such a thin-film EL display panel is normally driven by means of a relatively high voltage reaching about 200 VAC, for example.